I think Bowman coming here is more of a possibility that some realize. Apperantly the niners tried to trade him to another team but he refused to play for them and thus asked for a release. That suggests to me that he's trying to go play for a contender. And I think we are one of the likelier options. Let me go through all of them.
Dallas: Possible, but not as likely as some would like. He'd be a good fit in that defense in the long run if his athleticism becomes somewhat of what it once was, and he and Sean Lee would make a formidable duo and that would not impede Jaylon Smith's development as much as some would suggest. However, Dallas needs for more than him and it's unclear if they will be able to get that help any time soon. So while his is possible, I wouldn't think it's the likeliest choice.
Oakland: Most likely option. That defense is overall a rock solid unit when healthy, but has a piss poor ILB group. Adding a mind like Bowman onto the team gives him the opportunity to help cover up some of their problems. Inclusive in run defense. Not to mention, close to home, wouldn't have to move. Not than a rich NFL player couldn't afford a temporary apartment in the city while proceeding with a full move in the offseason.
Houston: Nope. Not happening. Defense may have a ton of talent, but it is currently decimated with more injuries with regards to elite talent than we could possibly fathom. Not to mention both of their inside linebackers with regards to Zach Cunningham and Benardrick McKinley are both good players, and while Brian Cushing is overrated, he's still more than capable of being a good player when he returns from suspension. Don't see it.
New England: very likely sadly. I think he wants to play for a contender and that the money isn't as important to him as some would think. While they have Donta' Hightower, the rest of that inside linebacker corps is uninspiring as is that defense as a whole. Bowman would certainly make them a more formidable unit. He'd have to take a paycut, but if this happens he's esentially guarenteed one trip to a super bowl.
Indianapolis Colts: Wants to play for a contender. Although the colts are currently not a contender, if they put together a good defense and get a solid running game in place for Andrew Luck that could change quickly. This is a possibility that should not be discounted.
New Orleans Saints: I'll be damned if this happens btw.
Us: Lots of young talent on the defense that's only going to get better with age. Two good coverage linebackers with Mosley and Bowser are currently in place. Bowman would turn into a coach on the field and serve as more of an ILB #2. He's been struggling in coverage, but is still a good blitzer and run defender, and could rebound as a coverage linebacker. Next year the secondary is also set to be a stout one. I think if we could pull off some cap wizardry bullishit, we are in the top 3 teams for the running. Plus he seems to like the Harbaughs.